1. The Field of the Invention
This invention relates to electromagnetic simulation of bone stress, and more particularly to methods and apparatus to stimulate or otherwise induce electrical activity in bones of a subject in order to elicit a positive response such as natural generation of increased bone density.
2. The Background Art
Human tissues are electrical apparatus. Likewise animal tissues are electrical apparatus. A complex assembly of structure, chemistry, and electrical connection controls and implements the activity, growth, healing, and other functions of living tissues of the animal kingdom. Manipulating the structures of tissues, whether soft tissue or bone tissue has been purview of the surgical portion of the medical community. Manipulation of chemistry has been the purview the drug portion of the medical community. Manipulation of the electrical activities of body tissues has largely been left to the other two fields, surgical and chemical treatments.
There has been a development of an electrical treatment community in the medical field, particularly, dealing with electro-stimulation. However, many researchers in the field often claim a lack of understanding of the specific phenomena that affect the correlation between electrical stimulation and organic functioning of live animal tissues. Nevertheless, electrical stimulation therapy has been used in both invasive and noninvasive systems for directly applying electrical potential to stimulate a response.
Within the medical community, selected, time-varying electric and magnetic fields have played an increasingly successful role in the care of several challenging medical problems, mainly fractures that have failed to heal, in both children and adults, as well as chronic skin wounds. This progress has been made over the past decades.
Bioelectromagnetics is a term applied to a field developing in the biological sciences and devoted to the interaction between living organisms and electro-magnetic fields. Electrical phenomenon are inherent in most living organisms, and certainly in all animal organisms. For example bones, nerves, cartilage, muscle, and the like have been considered to contain electrical connections and circuits for their normal operation. Accordingly, these electrical circuits can be influenced by external magnetic fields and electromagnetic fields. Publications indicate that electromagnetic fields operating at frequencies below 300 hertz can influence biological functions. Some controversy exists regarding the mechanics of operation of these interactions.
Pulsed electromagnetic fields in medicine are not new. Static magnets and electrical current have been used for years. In modern medicine however, it was in about the 1970's that the United States FDA approved a pulsed electromagnetic field device to assist in the healing of non-union fractures. Doctor C. A. L. Basset pioneered work leading to an 80% success rate in the healing of non-union fractures without any side effects. Accordingly, therapy by pulsed electromagnetic fields is recognized as effective in bone healing in the medical profession.
Meanwhile, additional detailed work has been done on a cellular level in vitro and in vivo to evaluate the efficacy of pulsed electromagnetic fields on bone density. Much of the work seems to be devoted to establishing a specific biological mechanisms by which electromagnetic fields couple to body chemistry and cellular activity.
With the magnetic fields induced by an MRI machine, molecular dipoles orient along the magnetic field lines. Once the magnetic field is collapsed, the dipoles, actual physical molecules, rotate back to their original positions. The return to the original positions generates another magnetic pulse, which pulse is detected and used to reconstruct in a computer an image of the tissues within the MRI field.
Thus, electromagnetic fields are not only known to affect body tissues, but body tissues themselves generate magnetic fields by their own motion, which magnetic fields are sufficiently strong to be detected and analyzed by sophisticated signal processing in order to image tissues and boundaries of tissues in the body.
Likewise, the bone structures of a body are known to have a piezoelectric characteristic. That is, they respond to stress by creating an electrical potential. Likewise, however, since piezoelectric events are symmetric. The application of electrical potential will then cause stress.
What is needed is a system implementing a method and apparatus for coupling, non-invasively, an external electromagnetic field to the body tissues that may provide electrical stimulation to bones.
It would be an advance in the art to improve non-invasive electro-stimulation by magnetic coupling of an electrical system outside of a subject with the electrical system within a subject.